Rocker Jon Bon Jovi has helped to surprise a young boy with an inoperable brain tumour by making a guest appearance at his pediatric cancer research fundraiser.

Mario Carpino launched a Facebook.com campaign earlier this year (14) to persuade the Bon Jovi frontman to attend his lemonade stand fundraiser.

He hosted his fourth annual event in Bon Jovi's native New Jersey on Saturday (07Jun14) and the 52-year-old singer shocked his young fan by making an unannounced appearance to sign autographs and pose for pictures with Carpino and fans.

Mario's mum, Anna Carpino, tells Yahoo Shine, "Little did we know that he would just show up and surprise me. As much as I wanted it to be him, I thought it couldn't happen. I just started breaking down, crying, and shaking. I was a hot mess!"

She later added on Facebook.com, "Thank you Jon for making Mario's dream come true."